Honda warrants the seatbelts for life...That shit is a safety issue...get to your nearest Honda dealer ASAP and let them mess with it.
In the meantime - Does it 'try' to move when you open the door? Does it make any noise? Did it come off the track or get something stuck in it? Did you check fuses? I would assume the two auto seatbelts would BOTH quit if a fuse was blown, but I haven't checked that closely.
HTH
